Natural tooth composite material bone grafting scaffold for alveolar bone repair and design and preparation method thereof

Abstract

The invention belongs to the technical field of biomedical materials, and discloses a natural tooth composite material bone grafting scaffold for alveolar bone repair and a design and preparation method thereof. The method comprises the following steps: collecting orthodontic teeth, impacted teeth, multiple teeth, loose teeth and other natural teeth extracted in oral medical treatment, and performing technical treatment to obtain raw material powder; ball-milling and mixing the bioactive glass powder, the carbon-based material powder and the natural dental powder to obtain mixed powder; the mixed powder is used as a raw material, and the bone grafting scaffold is obtained through computer aided design and digital light processing technology 3D printing; and modifying the surface of the 3D printing bracket by using the polydopamine-carbon-based material composite coating to obtain the natural tooth composite material bone grafting bracket. The natural tooth composite material bone grafting scaffold obtained by the invention has good mechanical property, controllable degradation property and antibacterial property, and has good biocompatibility and osteogenesis efficiency.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of biomedical materials, and particularly relates to a natural tooth composite bone grafting scaffold for alveolar bone repair, a design and a preparation method. BACKGROUND

[0002] Alveolar bone defects caused by tooth loss, trauma, tumors, infections, etc. are a major problem in oral implantation, seriously affecting the oral health and quality of life of patients. Autologous bone transplantation is considered the "gold standard" for alveolar bone reconstruction, but the limitations of autologous bone transplantation, such as insufficient bone material in the donor area, postoperative infection and various potential complications, have seriously restricted its clinical application.

[0003] Natural tooth bone grafting materials are a new type of biomaterials that are expected to be applied to alveolar bone defect reconstruction, and have similar chemical inorganic salt components, crystal structures and biological properties to bone tissue. Unlike limited autologous bone grafts, a large number of teeth (impacted teeth, supernumerary teeth, orthodontic teeth, etc.) are usually removed and discarded as medical waste in daily oral medical treatment. Therefore, the rational use of natural teeth as tooth-derived bone grafting materials can provide an adequate and convenient source for bone defect repair materials. However, there are limitations in the current application of natural teeth in oral clinical practice, and only by crushing the extracted teeth into different shapes and sizes of debris, they are used for maxillary sinus lifting, guided bone regeneration surgery, alveolar fossa preservation, etc., such as the research of Kim[1], Pang[2], Xie[3] etc. In the repair of alveolar bone defects, especially in alveolar bone vertical bone augmentation surgery, the crumb-shaped natural tooth material exposes obvious defects, including insufficient osteogenesis, poor mechanical stability, rapid absorption, complex surgical operation, etc.

[0004] REFERENCES

[0005] [1] Kim YK, Lee J, Um IW, et al. Tooth-derived bone graft material. J Korean Assoc Oral Maxillofac Surg. 2013;39(3):103-11.

[0006] [2]Pang KM, Um IW, Kim YK, et al. Autogenous demineralized dentin matrix from extracted tooth for the augmentation of alveolar bone defect: a prospective randomized clinical trial in comparison with anorganic bovine bone. Clin Oral Implants Res. 2017;28(7):809-815.

[0007] [3]Jing X, Xie B, Li X, et al. Peptide decorated demineralized dentin matrix with enhanced bioactivity, osteogenic differentiation via carboxymethyl chitosan. Dent Mater. 2021;37(1):19-29.

[0008] Bone tissue engineering scaffolds have important application prospects in the treatment of alveolar bone defects, and the core functional requirements are clear: it not only needs to maintain the osteogenesis space, but also needs to have controllable degradation ability to realize the dynamic balance between new bone growth and scaffold degradation. To meet the above requirements, material selection and preparation technology are crucial. At the material level, the mixed material with natural tooth powder as the base material, composite bioactive glass powder and carbon-based material powder, has enough mechanical properties to maintain the osteogenesis space, and has controllable degradation ability to regulate the degradation rate; at the preparation technology level, additive manufacturing technology provides a basis for the precise design and preparation of the scaffold, and its digital light processing technology can not only be used to manufacture high-precision and high-performance porous bone graft scaffolds, but also be used to manufacture patient bone defect customized matching scaffolds, which lays a technical support for the realization of the function of the scaffold. SUMMARY

[0009] In order to overcome the problems existing in the prior art, the present application discloses a natural tooth composite bone graft scaffold for alveolar bone repair, a design and preparation method.

[0010] The technical solution is as follows: a preparation method of a natural tooth composite bone graft scaffold for alveolar bone repair, comprising the following steps:

[0011] S1, collecting natural teeth including orthodontic teeth, impacted teeth, supernumerary teeth, loose teeth removed in oral medical treatment, and obtaining natural tooth powder by processing;

[0012] S2, ball-milling the bioactive glass powder, the carbon-based material powder, and the natural tooth powder to obtain a mixed powder;

[0013] S3, constructing a three-dimensional scaffold model by using computer-aided design, and combining bionic trabecula and three-period minimal surface to design the structure;

[0014] S4, taking the mixed powder as raw material, and obtaining the 3D bone grafting scaffold by digital light processing 3D printing;

[0015] S5, modifying the surface of the 3D bone grafting scaffold by using a polydopamine-carbon-based material composite coating to obtain a natural tooth composite bone grafting scaffold.

[0016] In step S1, the preparation method of the natural tooth powder comprises the following steps:

[0017] S101, pre-washing and disinfecting the natural tooth;

[0018] S102, removing the soft and hard tissue attachments on the surface of the natural tooth;

[0019] S103, ultrasonic cleaning, and ultrasonic cleaning the natural tooth with normal saline and sterile PBS;

[0020] S104, freeze-drying, freeze-drying the natural tooth after ultrasonic cleaning by using a freeze-drying machine;

[0021] S105, crushing and screening, crushing the treated natural tooth under sterile conditions, and screening the natural tooth powder with a particle size of less than 150 µm on a filter screen.

[0022] In step S105, the natural tooth powder with a particle size of less than 150 µm screened on the filter screen further comprises: screening the natural tooth powder with a particle size of less than 50 µm on a 300-mesh filter screen.

[0023] In step S2, the preparation method of the mixed powder is as follows:

[0024] S201, adding bioactive glass powder to the natural tooth powder, ball-milling for 1 h-2 h, and fully mixing to obtain an intermediate powder; wherein the bioactive glass powder is MgO-CaO-P2O5-SiO2-F or CaO-P2O5-SiO2, the powder particle size is less than 50 µm, and the addition ratio is 5%-20% of the mass of the natural tooth powder;

[0025] S202, add carbon-based material powder to the intermediate powder, ball mill for 1-2 hours, mix well to obtain a mixed powder; wherein the carbon-based material powder is one or more of carbon nanotubes, carbon nanofibers, graphene, and graphyne, and the addition ratio is 0.1%-1% of the mass of the natural tooth powder.

[0026] In step S4, the preparation method of the 3D bone grafting support includes:

[0027] S301, preparing a light-curing forming slurry based on the mixed powder, the preparation raw materials including the mixed powder, a photosensitive resin premix, and a dispersing agent; the weight components are: 55wt%-75wt% of the mixed powder, 25wt%-45wt% of the photosensitive resin premix, and 2wt%-4wt% of the dispersing agent; the photosensitive resin premix is a mixture of acrylate monomers, a photoinitiator, and an auxiliary agent, the photoinitiator is 0.5wt%-2wt% of the weight of the photosensitive resin premix, and the auxiliary agent is 0.1wt%-2wt% of the weight;

[0028] S302, 3D printing a 3D bone grafting support pre-treatment body through a digital light processing process, and obtaining the 3D bone grafting support through cleaning, debinding, and sintering processes after the 3D bone grafting support pre-treatment body is printed.

[0029] In step S301, the acrylate monomers include at least one or more of a mixture of trimethylolpropane triacrylate TMPTA, tripropylene glycol acrylate TPGDA, 1,6-hexanediol diacrylate HDDA, 4-acryloylmorpholine ACMO, and 2-hydroxyethyl methacrylate HEMA;

[0030] The photoinitiator is one or more of diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide, 2,4,6-trimethylbenzoyl phenyl phosphonic acid ethyl ester, fluoro borate acrylate, and 2-hydroxy-2-methyl-1-phenyl-1-propanone;

[0031] The dispersing agent includes at least one of sodium tripolyphosphate, carboxymethyl cellulose, sodium polyacrylate, and ammonium polymethacrylate;

[0032] The auxiliary agent is one or a mixture of two or more of a leveling agent, a defoaming agent, an absorbent, a polymerization inhibitor, an inhibitor, a stabilizer, and a sintering aid.

[0033] In step S301, the preparation method of the light-curing forming slurry based on the mixed powder includes the following steps:

[0034] Step 1, obtaining a mixed powder of natural teeth, bioactive glass, and carbon-based material;

[0035] Step 2, 0.5wt%-2wt% of a photoinitiator and an auxiliary agent are added into the acrylic ester monomer, and a resin premix is obtained by stirring at room temperature for 2h-5h through a magnetic stirrer;

[0036] Step 3, 55wt%-75wt% of the mixed powder and 2wt% of a dispersant based on the weight of the mixed powder are added into the obtained resin premix, and ball milling is performed for 2h-3h or homogenization is performed for 2min-6min using a homogenizer; wherein the mixed powder is added in three times, and after the mixed powder is completely added, ball milling is continuously performed for 2h-3h or homogenization is performed for 2min-6min using a homogenizer, to obtain a light-curing molding slurry based on the mixed powder.

[0037] In step S4, the preparation method of the composite bone grafting support includes:

[0038] S401, dopamine hydrochloride is dissolved in a Tris-HCL buffer solution with pH=8.5 in an ultra-clean bench; and a 3D bone grafting support is placed in the Tris-HCL buffer solution for 12h-48h under ventilation and dark conditions, so that dopamine is self-polymerized and adhered to the support;

[0039] S402, then, carbon-based material powder is prepared into a solution using deionized water, the above support is placed in the carbon-based material solution for 5min-10min and then taken out, modification is completed, and finally a composite bone grafting support modified by a polydopamine-carbon-based material composite coating is obtained;

[0040] In step S401, the Tris-HCL buffer solution is prepared into a solution with a concentration of 1mg / mL-3mg / mL; the 3D bone grafting support is placed in the solution for 12h-48h, so that dopamine is self-polymerized and adhered to the support; after modification, the support is washed with sterile deionized water for 3 times to completely remove unbound dopamine;

[0041] In step S402, the carbon-based material is prepared into a solution with a concentration of 1mg / mL-3mg / mL.

[0042] Another object of the present application is to provide a natural tooth composite bone grafting support for alveolar bone repair, which is prepared by using the preparation method of the natural tooth composite bone grafting support for alveolar bone repair.

[0043] Another object of the present application is to provide a design method of a natural tooth composite bone grafting support for alveolar bone repair, which is used to improve the preparation method of the natural tooth composite bone grafting support for alveolar bone repair, and the design method includes:

[0044] (1) Block bone grafting support: use computer aided design to construct bone grafting support model; wherein the internal porous structure of the block bone grafting support includes but is not limited to bionic trabecula, three-periodic minimal surface, tetrahedron, hexahedron, octahedron, diamond structure, the pore size of the support is 250-800 μm, the wire diameter is 100-400 μm, and the porosity is 60-80%; the external structure is in the shape of cylinder, cube, rectangle, ring, and wedge.

[0045] (2) Granular bone grafting support: use computer aided design to construct bone grafting support model; wherein the internal porous structure of the granular support includes but is not limited to bionic trabecula, three-periodic minimal surface, tetrahedron, hexahedron, octahedron, diamond structure, the pore size of the support is 250-800 μm, the wire diameter is 100-400 μm, and the porosity is 60-80%; the external structure is in the shape of granule, and the size is 0.5-3 mm.

[0046] (3) Patient matching bone grafting support: reconstruct alveolar bone according to CBCT image data, and virtually repair alveolar bone defect; determine the three-dimensional shape and size of the customized support according to the bone defect area, and perform porous design; wherein the porous structure of the support includes but is not limited to bionic trabecula structure and three-periodic minimal surface structure, the pore size of the support is 250-800 μm, the wire diameter is 100-400 μm, and the porosity is 60-80%. Another object of the present application is to provide an application of the natural tooth composite bone grafting support for repairing alveolar bone in the preparation of oral implant for alveolar bone defects caused by tooth loss, trauma, tumor, and infection, which is prepared by the preparation method of the natural tooth composite bone grafting support for repairing alveolar bone.

[0047] In combination with all the above technical solutions, the present application has the following beneficial effects:

[0048] Firstly, the present application collects natural teeth such as orthodontic teeth, impacted teeth, supernumerary teeth, and loose teeth in oral medical treatment, and obtains raw material powder through processing; bioactive glass powder, carbon-based material powder, and natural tooth powder are ball milled and mixed to obtain a mixed powder; the mixed powder is used as raw material to obtain a bone grafting support through computer aided design and digital light processing technology 3D printing; the surface of the 3D printed support is modified using a polydopamine-carbon-based material composite coating to obtain a natural tooth composite bone grafting support. The natural tooth composite bone grafting support obtained by the present application has good mechanical properties, controllable degradation performance, and antibacterial performance, and has good biocompatibility and osteogenic efficiency.

[0049] Second, the global oral bone repair material market has reached 6.969 billion US dollars in 2022 due to factors such as population aging and increasing oral diseases. It is expected that from 2023 to 2030, the market will continue to grow at a compound annual growth rate (CAGR) of 9.5%. According to the latest industry data and forecasts in 2025, the annual tooth extraction volume in China is about 25-30 million. The invention converts traditional medical waste into a new type of bone graft material, solves the pain points of traditional technology, meets the clinical needs, and provides a reliable clinical solution for alveolar bone defects.

[0050] Third, in the oral clinical bone grafting, the processing method of the extracted teeth is generally to make them into crumb-shaped materials. However, this method has problems such as insufficient osteogenesis space maintenance ability, poor bone regeneration effect, and unstable clinical effect, which makes it difficult to be widely used. The present invention can be precisely designed and formed on the micro-pore, improving the osteogenesis space and blood supply nutrient transmission capacity; the macro-configuration can be customized according to the patient's defect, and it is suitable for the bone defect area. These improved features realize innovation breakthroughs for the defects of the prior art.

[0051] In the traditional oral clinical practice of alveolar bone defect repair (especially vertical bone augmentation surgery), the method of grinding the extracted teeth into crumb and then using them has long been a difficult problem that has not been effectively solved, such as poor osteogenesis effect, poor mechanical stability, and weak osteogenesis space maintenance ability. These problems have been the key to be overcome in clinical practice in order to improve the surgical effect. The present invention effectively addresses this clinical problem by precise design of micro-pores, individualized customization of macro-configuration, and application of additive manufacturing technology, successfully solving the long-standing technical problem that has not been overcome in clinical practice.

[0052] Fourth, for the application of extracted teeth, the method of grinding into crumb is usually used, which forms the inertial cognition that "using crumb-shaped materials for related repair is a common and effective method". However, the present invention solves this problem through the innovative design of the bracket and the additive manufacturing technology, breaking through the inertial cognition formed in the industry for a long time with a new technical solution. BRIEF DESCRIPTION OF DRAWINGS

[0053] The accompanying drawings, which are incorporated into the specification and constitute a part of it, illustrate embodiments consistent with the present disclosure and, together with the specification, serve to explain the principles of the present disclosure;

[0054] Figure 1 is a preparation method flowchart of the natural tooth composite material bone graft bracket for alveolar bone repair provided by the embodiment of the present invention;

[0055] Figure 2 is a physical diagram of the natural tooth composite material block-shaped bone graft bracket provided by the embodiment of the present invention;

[0056] Figure 3 is a physical diagram of the natural tooth composite granular bone grafting scaffold provided by the embodiment of the present application;

[0057] Figure 4 is a design diagram of the natural tooth composite patient-matched bone grafting scaffold provided by the embodiment of the present application;

[0058] Figure 5 is a physical diagram of the natural tooth composite patient-matched bone grafting scaffold provided by the embodiment of the present application. DETAILED DESCRIPTION

[0059] In order to make the above objectives, features and advantages of the present application more apparent, specific embodiments of the present application are described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, the present application can be practiced in a number of different ways beyond the specific details described herein. It is, therefore, to be understood that the present application is not limited to the specific embodiments disclosed below and that modifications can be made by one skilled in the art without departing from the scope of the present application.

[0060] The innovation of the present application is that:

[0061] Firstly, a technical scheme based on digital light processing technology is established from raw material preparation to bone grafting scaffold application. By optimizing the key process parameters, the mechanical properties of the natural tooth composite scaffold are ensured to be consistent. This breakthrough solves the problem of poor mechanical properties of traditional natural tooth crumb materials and unstable clinical effects, and provides a reliable manufacturing process chain for alveolar bone defects.

[0062] Secondly, through computer-aided design and numerical simulation, the geometric parameters of the bone grafting scaffold, including the pore structure, pore size and porosity, can be accurately selected and adjusted, directly improving the structural precision of the scaffold, and creating an ideal bone integration environment for cell infiltration, vascularization and bone tissue regeneration. The present application can design, optimize and manufacture patient-matched alveolar bone regeneration scaffolds according to different alveolar bone defect geometries (shape, size, position), which is an advantage that cannot be achieved by traditional methods.

[0063] Finally, the reuse of medical waste can be converted into bone grafting materials, which can be used for various bone defect repair cases in the field of oral medicine, covering but not limited to oral implant surgery, periodontology, oral and maxillofacial surgery and other clinical departments, and is expected to break through the clinical technical bottleneck of bone defect repair.

[0064] As shown in Figure 1 the preparation method of the natural tooth composite bone grafting scaffold for alveolar bone repair provided by the embodiment of the present application includes the following steps:

[0065] S1, collecting natural teeth including orthodontic teeth, impacted teeth, supernumerary teeth, loose teeth removed in oral surgery, and obtaining natural tooth powder by processing;

[0066] S2, ball milling the bioactive glass powder, carbon-based material powder and natural tooth powder to obtain a mixed powder;

[0067] S3, constructing a three-dimensional scaffold model using computer-aided design, and combining bionic trabeculae and three-period minimal surface creation formula design structure;

[0068] S4, using the mixed powder as raw material, and obtaining a 3D bone grafting scaffold by digital light processing 3D printing;

[0069] S5, using a polydopamine-carbon-based material composite coating to modify the surface of the 3D bone grafting scaffold to obtain a natural tooth composite bone grafting scaffold.

[0070] Illustratively, the natural tooth powder preparation method in step S1 is as follows:

[0071] S101, pre-washing and disinfecting the natural teeth.

[0072] Selecting a tooth extraction patient without infectious diseases, and after the patient's informed consent, extracting the affected teeth such as orthodontic teeth, impacted teeth, supernumerary teeth, loose teeth, residual roots and crowns, etc. in the oral surgery outpatient department.

[0073] Soaking the extracted teeth in 3% hydrogen peroxide for 2 hours, then washing them with physiological saline to remove blood stains and blow-drying.

[0074] S102, removing the soft and hard tissue attachments on the surface of the natural teeth.

[0075] Using a periodontal curette and a high-speed handpiece to remove soft debris, periodontal membrane, calculus, pigments, and carious tissue, etc.

[0076] S103, ultrasonic cleaning.

[0077] Placing the natural teeth in an ultrasonic cleaning instrument, and ultrasonically cleaning them with physiological saline for 10 minutes, and then ultrasonically cleaning them with sterile PBS (phosphate buffer solution containing 1% penicillin-streptomycin mixture) for 10 minutes.

[0078] S104, freeze-drying.

[0079] Discarding the PBS solution, sealing, storing at -20℃ for 2 hours, then pre-freezing in a -80℃ refrigerator for 24 hours, and then freeze-drying in a freeze-drying machine.

[0080] S105, crushing and screening.

[0081] The teeth after freeze-drying treatment by the special pulverizer are crushed under sterile conditions, and the natural tooth powder with a particle size of 150 µm or less is screened out on a 100-mesh screen.

[0082] For example, in the step S2, the mixed powder is prepared as follows:

[0083] S201, the bioactive glass powder is added to the natural tooth powder, ball milling for 1-2 hours, and fully mixed to obtain an intermediate powder; wherein the bioactive glass powder is MgO-CaO-P2O5-SiO2-F or CaO-P2O5-SiO2, the powder particle size is less than 50 μm, and the addition ratio is 5%-20% of the mass of the natural tooth powder.

[0084] S202, the carbon-based material powder is added to the intermediate powder, ball milling for 1-2 hours, and fully mixed to obtain the final mixed powder; wherein the addition ratio of the carbon-based material powder is 0.1%-1% of the mass of the natural tooth powder.

[0085] For example, in the preparation of the mixed powder, the process parameter screening process is as follows:

[0086] Orthogonal experiment: L9(3 2 ) orthogonal experiment (2 factors and 3 levels, 2 key factors of bioactive glass addition ratio and carbon-based material addition ratio) is used to screen the process parameters for preparing the mixed powder.

[0087] Evaluation index and test method: slurry viscosity, slurry solidification forming precision, mechanical properties such as compressive strength, elastic modulus, and fracture toughness, and mineralization potential, etc., and finally the parameter range of bioactive glass addition ratio 5%-20% and carbon-based material addition ratio 0.1%-1% is screened out. Through screening the composition and ratio of the mixed powder, the prepared bone grafting scaffold has good mechanical properties and bioactivity.

[0088] Another object of the present application is to provide a design method of a natural tooth composite bone grafting scaffold for alveolar bone repair, which is used to improve the preparation method of the natural tooth composite bone grafting scaffold for alveolar bone repair, and the design method comprises:

[0089] (1) Block bone grafting scaffold: a computer-aided design is used to construct a bone grafting scaffold model; wherein the internal porous structure of the block bone grafting scaffold includes but is not limited to bionic bone trabecula, three-periodic minimal surface, tetrahedron, hexahedron, octahedron, diamond, etc., the pore size of the scaffold is 250 μm-800 μm, the wire diameter is 100 μm-400 μm, and the porosity is 60%-80%; the external structure is in the shape of cylinder, cube, rectangle, circular ring, and wedge.

[0090] (2) Granular bone grafting scaffold: using computer-aided design to construct a bone grafting scaffold model; wherein the internal porous structure of the granular scaffold includes but is not limited to bionic trabecula, three-period minimal surface, tetrahedron, hexahedron, octahedron, and diamond structure, the pore size of the scaffold is 250 μm-800 μm, the wire diameter is 100 μm-400 μm, and the porosity is 60%-80%; the external structure is granular, and the size is 0.5 mm-3 mm.

[0091] (3) Patient-matched bone grafting scaffold: reconstructing alveolar bone according to CBCT image data, virtually repairing alveolar bone defects; determining the three-dimensional shape and size of the custom-designed scaffold according to the bone defect area, and designing the scaffold to be porous; wherein the porous structure of the scaffold includes but is not limited to bionic trabecula structure, three-period minimal surface, etc., the pore size of the scaffold is 250 μm-800 μm, the wire diameter is 100 μm-400 μm, and the porosity is 60%-80%. In an example, in step S3, the preparation method of the 3D bone grafting scaffold is as follows:

[0092] S301, preparing a light-curing forming slurry based on mixed powder, the preparation raw materials including the mixed powder of step S2, a photosensitive resin premix, and a dispersing agent. The weight components are: mixed powder 55wt%-75wt%, photosensitive resin premix 25wt%-45wt%, and dispersing agent 2wt%-4wt% of the mixed powder. The photosensitive resin premix is a mixture of acrylate monomers, a photoinitiator, and an auxiliary agent, the photoinitiator is 0.5wt%-2wt% of the weight of the photosensitive resin premix, and the auxiliary agent is 0.1wt%-2wt%.

[0093] The process parameter screening process of step S301 includes:

[0094] Orthogonal experiment: L9(3 3 Orthogonal experiment (3 factors and 3 levels, 3 key factors of mixed powder proportion, photosensitive resin premix proportion, and dispersant amount) to screen the process parameters of the light-curing forming slurry.

[0095] Evaluation index and test method: slurry viscosity, curing depth, slurry curing forming precision, and slurry curing interlayer bonding capacity are used to screen the parameter range of the light-curing forming slurry preparation. Through screening the composition and ratio of the slurry and the appropriate amount of dispersing agent, the prepared slurry has high solid content and low viscosity.

[0096] Preferably, the acrylate monomer includes at least one or a mixture of multiple of trimethylolpropane triacrylate (TMPTA), tripropylene glycol diacrylate (TPGDA), 1,6-hexanediol diacrylate (HDDA), 4-acryloylmorpholine (ACMO), and 2-hydroxyethyl methacrylate (HEMA).

[0097] Preferably, the photoinitiator is one or more of diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide, phenyl bis (2,4,6-trimethylbenzoyl) phosphine oxide, 2,4,6-trimethylbenzoyl phenyl phosphonic acid ethyl ester, fluoro borate acrylate, 2-hydroxy-2-methyl-1-phenyl-1-propanone.

[0098] Preferably, the dispersant includes at least one of sodium tripolyphosphate, carboxymethyl cellulose, sodium polyacrylate, ammonium polymethacrylate.

[0099] Preferably, the auxiliary agent is one or a mixture of two or more of a leveling agent, a defoaming agent, an absorbent, a polymerization inhibitor, an inhibitor, a stabilizer, a sintering aid.

[0100] The preparation method of the mixed powder-based photocuring molding slurry includes the following steps:

[0101] Step 1, obtaining a mixed powder of natural teeth, bioactive glass and carbon-based material;

[0102] Step 2, adding 0.5wt%-2wt% of a photoinitiator and an auxiliary agent to an acrylate monomer, and stirring at room temperature for 2h-5h by a magnetic stirrer to obtain a resin premix;

[0103] Step 3, adding 55wt%-75wt% of the mixed powder and 2wt% of the dispersant based on the weight of the mixed powder to the obtained resin premix, and ball milling for 2h-3h or homogenizing for 2min-6min using a homogenizer. Preferably, the mixed powder is added in three times, and after the mixed powder is completely added, the ball milling is continued for 2h-3h or the homogenizing is continued for 2min-6min using a homogenizer, to obtain the mixed powder-based photocuring molding slurry.

[0104] Illustratively, the process parameter screening process in the preparation of the mixed powder-based photocuring molding slurry includes:

[0105] Orthogonal experiment: L9(3 3 Orthogonal experiment (3 factors and 3 levels, 3 key factors of mixed powder proportion, photosensitive resin premix proportion, and dispersant amount) is used to screen the process parameters of the photocuring molding slurry.

[0106] Evaluation index and test method: the slurry viscosity, curing depth, slurry curing molding precision, and slurry curing interlayer bonding capacity are used to screen the parameter range of the preparation of the photocuring molding slurry.

[0107] S302, preprocessing the 3D bone grafting support by digital light processing 3D printing, and obtaining the 3D bone grafting support through cleaning, debinding, sintering and other processes after the 3D bone grafting support preprocessing body is printed.

[0108] For example, in step S4, the preparation method of the composite bone grafting scaffold is as follows:

[0109] S401, dissolve dopamine hydrochloride in a Tris-HCL (Tris (Hydroxymethyl) Aminomethane Hydrochloride) buffer solution with pH = 8.5 to prepare a 1 mg / mL-3 mg / mL solution in an ultra-clean bench. Place the 3D bone grafting scaffold in the solution for 12-48 hours under ventilation and darkness, and dopamine is self-polymerized and adhered to the scaffold. After modification, wash the scaffold with sterile deionized water for 3 times to completely remove the unbound dopamine.

[0110] S402, then prepare a 1 mg / mL-3 mg / mL solution of the carbon-based material powder with deionized water, and take out the above scaffold after placing it in the carbon-based material solution for 5-10 minutes to complete the modification, and finally obtain a polydopamine-carbon-based material composite coating modified composite bone grafting scaffold.

[0111] In the preparation of the natural tooth composite bone grafting scaffold, the process parameter screening process includes:

[0112] Orthogonal experiment: L9(3 2 ) orthogonal experiment (2 factors and 3 levels, dopamine solution concentration and carbon-based material solution concentration are two key factors) is used to screen the parameter range of the composite coating solution concentration.

[0113] Evaluation index and test method: the parameter range of the dopamine / carbon-based material solution concentration is screened out by the coating thickness, biological activity and other indexes, so that the prepared natural tooth composite bone grafting scaffold has good biological activity.

[0114] Example 2, the application provides a natural tooth composite bone grafting scaffold for alveolar bone repair prepared by the preparation method of the natural tooth composite bone grafting scaffold for alveolar bone repair.

[0115] The application also provides an application of the natural tooth composite bone grafting scaffold for alveolar bone repair in the preparation of an oral implant for alveolar bone defect caused by tooth loss, trauma, tumor and infection, which is prepared by the preparation method of the natural tooth composite bone grafting scaffold for alveolar bone repair.

[0116] Example 3, select patients without infectious disease tooth extraction, after the patient's informed consent, in the oral surgery clinic to remove the teeth, such as orthodontic teeth, impacted teeth, supernumerary teeth, loose teeth, residual roots and crowns, etc. First, the extracted natural teeth were soaked in 3% hydrogen peroxide for 2 hours, then washed with physiological saline to remove blood stains and dried. The periodontal curette and high-speed handpiece were used to remove soft debris, periodontal membrane, calculus, pigments, carious tissue, etc. The instrument was placed in an ultrasonic cleaning instrument and washed with physiological saline for 10 minutes. The PBS (phosphate buffer solution containing penicillin-streptomycin mixture 1%) was replaced and ultrasonically cleaned for 10 minutes. The PBS solution was discarded, sealed, and stored at -20°C for 2 hours. Then it was transferred to a -80°C freezer for pre-freezing for 24 hours, and then placed in a freeze-drying machine for freeze-drying treatment. The freeze-dried teeth were crushed under sterile conditions using a special crusher, and the natural tooth powder with a particle size of 150 pm or less was screened out through a 100 mesh sieve and sealed for use.

[0117] The bioactive glass powder was added to the natural tooth powder, the powder particle size was less than 50 pm, the addition ratio was 10% of the mass of the natural tooth powder, and the ball milling was carried out for 1-2 h to obtain the intermediate powder. The carbon-based material powder was added to the intermediate powder, the addition ratio was 0.2% of the mass of the natural tooth powder, and the ball milling was carried out for 1-2 h to obtain the final mixed powder.

[0118] The photosensitive resin was mixed with the above-mentioned materials according to a weight ratio of 1:2 to obtain a 3D printing slurry. First, different types of acrylate monomers were added to a container, and 0.5wt% of a photoinitiator and an auxiliary agent (0.05% light absorber) were added. The resin premix was obtained by stirring at room temperature for 2-5 h using a magnetic stirrer; then, the mixed powder was added to the resin premix according to a weight ratio of 1:2, and a dispersing agent accounting for 2wt% of the weight of the natural tooth powder was added, and the ball milling was carried out for 2-3 h. Preferably, the natural tooth powder is added in three times, and the ball milling is continued for 2-3 h after the addition of the natural tooth powder to obtain the natural tooth 3D printing slurry.

[0119] Scaffold modeling: the modeling model of this embodiment is a three-period minimal surface structure with a diameter of 8 mm, a height of 5 mm, a pore size of 250-500 pm, a wire diameter of 200 pm, and a porosity of 60-80%.

[0120] The model data was imported into a 3D printer with a light source wavelength of 405 nm, and the printing parameters were set as follows: the printing layer thickness was 50 pm, and the exposure time was 5-20 s.

[0121] Based on the natural tooth powder as the raw material, a light-cured printing slurry was prepared, and a digital light processing technology was used for 3D printing. After printing, the scaffold was cleaned by ultrasonic cleaning to remove excess slurry, and a green body of the bone grafting scaffold was obtained.

[0122] The obtained bone grafting scaffold green body was heated at a heating rate of 1 ℃ / min to 200 ℃ for 2 h, heated at a heating rate of 0.5 ℃ / min to 400 ℃ for 2 h, heated at a rate of 1 ℃ / min to 1200 ℃ after debinding was completed, and kept for 4 h, and finally cooled to room temperature at a cooling rate of 5 ℃ / min to obtain the bone grafting scaffold.

[0123] The sintered scaffold was surface modified: soaked in a dopamine solution of 2 mg / mL for 12-48 h, and after modification, the scaffold was washed 3 times with sterile deionized water to completely remove unbound dopamine. Then it was soaked in a carbon-based material solution of 2 mg / mL, taken out after 5-10 min, and the modification was completed. Finally, a natural tooth composite bone grafting scaffold modified with a polydopamine-carbon-based material composite coating was obtained. As shown in the physical map of the natural tooth composite block bone grafting scaffold. Figure 2

[0124] Example 4, the difference between Example 4 and Example 3 is that the particle size of the natural tooth powder is smaller than 50 μm, and the proportion of the bioactive glass powder and the carbon-based material powder added in the slurry is different.

[0125] The natural tooth powder and the 3D printing slurry were prepared according to Example 1. Among them, the bioactive glass powder was added to the natural tooth powder, the powder particle size was less than 50 μm, the addition ratio was 15% of the mass of the natural tooth powder, and the ball milling time was 1-2 h to fully mix to obtain the intermediate powder. The carbon-based material powder was added to the intermediate powder, the addition ratio was 0.1% of the mass of the natural tooth powder, and the ball milling time was 1-2 h to fully mix to obtain the final mixed powder.

[0126] Modeling: Design a granular bone grafting scaffold with tetrahedral structure / hexahedral structure / octahedral structure / diamond structure / minimum curved surface structure, and the model size is less than 1 mm×1 mm×1 mm, the pore size is 250-500 μm, and the porosity is 60%-80%.

[0127] The model data was imported into a 3D printer with a light source wavelength of 405 nm, and the printing parameters were set as follows: the printing layer thickness was 20 μm, and the exposure time was 2-10 s.

[0128] After the above steps were completed, the workbench and the model were cleaned to obtain a granular bone grafting scaffold green body.

[0129] The obtained granular bone grafting scaffold green body was heated at a heating rate of 1 ℃ / min to 200 ℃ for 2 h, heated at a heating rate of 0.5 ℃ / min to 400 ℃ for 2 h, heated at a rate of 1 ℃ / min to 1200 ℃ after debinding was completed, and kept for 4 h, and finally cooled to room temperature at a cooling rate of 5 ℃ / min to obtain the granular bone grafting scaffold printed by the natural tooth powder; ​

[0130] The sintered granular bone graft scaffold is surface modified: soaked in a dopamine solution of 2 mg / mL for 12-48 h, and after modification, the bone graft particles are washed 3 times with sterile deionized water to completely remove unbound dopamine. Then soaked in a carbon-based material solution of 2 mg / mL, taken out after 5-10 min, complete modification, finally get polydopamine-carbon-based material composite coating modified natural tooth composite granular bone graft scaffold.

[0131] The real photo of the natural tooth composite granular bone graft scaffold shown by Figure 3 It can be seen from the real photo of the natural tooth composite granular bone graft scaffold shown by the embodiment that the granular bone graft scaffold obtained by the embodiment has a complete structure and no cracks can be seen with the naked eye, and has an interconnected three-dimensional pore structure.

[0132] Example 5, the difference between Example 5 and Example 4 and Example 1 is that the particle size of the natural tooth powder is smaller than 50 μm, the proportion of the bioactive glass powder and the carbon-based material powder added in the slurry is different, and the sintering temperature is different.

[0133] The natural tooth powder and the 3D printing slurry are prepared according to Example 1. Among them, the bioactive glass powder is added to the natural tooth powder, the powder particle size is less than 50 μm, the addition ratio is 20% of the mass of the natural tooth powder, ball milling for 1-2 h, and fully mixing to obtain the intermediate powder; the carbon-based material powder is added to the intermediate powder, the addition ratio is 0.5% of the mass of the natural tooth powder, ball milling for 1-2 h, and fully mixing to obtain the final mixed powder.

[0134] Modeling: based on patient imaging data (CBCT) for three-dimensional reconstruction, and extracting the morphological geometric parameters of the alveolar bone defect bone graft block. Then modeling the block porous bone graft scaffold, the alveolar bone defect is irregular, the size of the scaffold is: L x W x H = 13 x 14 x 7 mm, the pore size is 200 μm-500 μm, the wire diameter is 200 μm, and the porosity is 70%, the obtained model is as shown in Figure 4 The design effect diagram of the natural tooth composite patient-matched bone graft scaffold is shown;

[0135] The model data is imported into a 3D printer with a light source wavelength of 405 nm, and the printing parameters are set as follows: the printing layer thickness is 50 μm, and the exposure time is 5-10 s;

[0136] The above 3D printing slurry is used for 3D printing, and after printing, the green body of the patient-matched bone graft scaffold is obtained after cleaning;

[0137] The obtained patient-matched bone grafting scaffold green body was heated to 200°C at a heating rate of 1°C / min, kept for 2h; heated to 400°C at a heating rate of 0.5°C / min, kept for 2h; heated to 600°C at a heating rate of 2°C / min, kept for 2h; heated to 800°C at a heating rate of 2°C / min, kept for 2h; heated to 1250°C at a heating rate of 2°C / min, kept for 6h; finally, cooled to room temperature at a cooling rate of 5°C / min, to obtain the patient-matched bone grafting scaffold prepared from the mixed powder, as shown in Figure 5 .

[0138] The sintered scaffold was surface modified: soaked in a dopamine solution of 2mg / mL for 12h-48h, and after modification, the scaffold was washed with sterile deionized water for 3 times to completely remove the unbound dopamine. Then, it was soaked in a carbon-based material solution of 2mg / mL, and after 5min-10min, it was taken out, and the modification was completed, finally obtaining the polydopamine-carbon-based material composite coating modified composite patient-matched bone grafting scaffold.

[0139] As shown in Figure 4 It can be seen that the design drawing of the composite patient-matched bone grafting scaffold obtained in this embodiment is complete in overall structure, and has a through three-dimensional pore structure; as shown in Figure 5 It can be seen that the patient-matched bone grafting scaffold obtained in this embodiment is complete in structure.

[0140] As shown in Figure 5 , the natural tooth composite bone grafting (porous bone grafting scaffold) for alveolar bone repair obtained in this embodiment is highly matched with the alveolar bone defect site.

[0141] Comparative example.

[0142] At present, there are limitations in the application of natural teeth in oral clinical practice, and only by crushing the extracted teeth into different shapes and sizes of debris, they are used for maxillary sinus lifting, guided bone regeneration surgery, alveolar cavity preservation, etc., such as the researches of Kim[1], Pang[2], Xie[3] and others. However, it should be particularly pointed out that in the repair of alveolar bone defects, especially in the alveolar bone vertical bone augmentation surgery, the crumb-shaped natural tooth material exposes obvious defects, including insufficient osteogenesis effect, poor mechanical stability, rapid absorption, and complex surgical operation.

[0143] Further, the existing clinical use methods for natural teeth, whether it is domestic autologous tooth bone powder, Japanese AutoBT, or other scholars' papers mentioned processing methods, all adopt crumb-shaped materials, which directly leads to the common problems of insufficient osteogenesis space maintenance ability and poor bone regeneration effect.

[0144] The improved features of the application in application include that the micro-pores can be precisely designed and accurately formed, the bone formation space capacity and blood nutrient transmission capacity are effectively improved, and the randomness and uncertainty of the traditional crumb-shaped autologous tooth bone powder are avoided.

[0145] The macro-configuration can be customized according to the shape of the defect of the patient, so that the bone graft material is better fitted to the wound area, and the randomness and uncertainty of the manual operation of the doctor are reduced.

[0146] In the above embodiments, the description of each embodiment has its own emphasis, and the parts not described or recorded in a certain embodiment can be referred to the related description of other embodiments.

[0147] The above is only a preferred specific embodiment of the application, but the protection scope of the application is not limited thereto, any modification, equivalent replacement and improvement made by any person skilled in the art within the technical range disclosed by the application and within the spirit and principles of the application should be covered within the protection scope of the application.

Claims

1. A method for preparing a natural tooth composite bone grafting scaffold for alveolar bone repair, characterized by, The preparation method comprises the following steps: S1, collecting natural teeth including extracted orthodontic teeth, impacted teeth, supernumerary teeth, loose teeth in oral medical treatment, and obtaining natural tooth powder by processing; S2, ball-milling and mixing bioactive glass powder, carbon-based material powder and natural tooth powder to obtain mixed powder; S3, constructing a three-dimensional support model by computer-aided design, and combining bionic trabecula and three-periodic minimal surface to design the structure; S4, using the mixed powder as raw material, and obtaining the 3D bone grafting support by digital light processing technology 3D printing; S5, using polydopamine-carbon-based material composite coating to modify the surface of the 3D bone grafting support, and obtaining the natural tooth composite bone grafting support.

2. The method for preparing a natural tooth composite bone grafting scaffold for alveolar bone repair according to claim 1, characterized in that, In step S1, the processing to obtain the natural tooth powder comprises: S101, pre-washing and disinfecting the natural tooth; S102, removing the soft and hard tissue attachments on the surface of the natural tooth; S103, ultrasonic cleaning, using physiological saline and sterile PBS to ultrasonically clean the natural tooth; S104, freeze-drying, freeze-drying the ultrasonically cleaned natural tooth in a freeze-drying machine; S105, crushing and screening, crushing the processed natural tooth under sterile conditions, and screening the natural tooth powder with a particle size of less than 150 µm on a filter screen.

3. The method of claim 2, wherein the natural tooth composite bone grafting scaffold for alveolar bone repair is prepared by the steps of: (a) mixing the natural tooth composite bone grafting scaffold for alveolar bone repair of claim 1 with a solvent; (b) stirring the mixture; (c) drying the mixture; and (d) pulverizing the dried mixture. In step S105, the natural tooth powder with a particle size of less than 150 µm screened on the filter screen further comprises: natural tooth powder with a particle size of less than 50 µm screened on a 300-mesh filter screen.

4. The method for preparing a natural tooth composite bone grafting scaffold for alveolar bone repair according to claim 1, characterized in that, In step S2, the preparation method of the mixed powder is as follows: S201, adding bioactive glass powder into the natural tooth powder, ball-milling for 1-2 hours, and fully mixing to obtain intermediate powder; wherein the bioactive glass powder is MgO-CaO-P2O5-SiO2-F or CaO-P2O5-SiO2, the powder particle size is less than 50 μm, and the addition ratio is 5%-20% of the mass of the natural tooth powder; S202, adding carbon-based material powder into the intermediate powder, ball-milling for 1-2 hours, and fully mixing to obtain the mixed powder; wherein the carbon-based material powder adopts one or more of carbon nanotubes, carbon nanofibers, graphene and graphyne, and the addition ratio is 0.1%-1% of the mass of the natural tooth powder.

5. The method for preparing a natural tooth composite bone grafting scaffold for alveolar bone repair according to claim 1, characterized in that, In step S4, the preparation method of the 3D bone grafting support comprises: S301, preparing a light-curing forming slurry based on the mixed powder, and the preparation raw material comprises the mixed powder, a photosensitive resin premix liquid and a dispersing agent; the weight components are: 55wt%-75wt% of the mixed powder, 25wt%-45wt% of the photosensitive resin premix liquid, and 2wt%-4wt% of the mixed powder as the dispersing agent; the photosensitive resin premix liquid is a mixture of acrylate monomers, a photoinitiator and an auxiliary agent, the photoinitiator is 0.5wt%-2wt% of the weight of the photosensitive resin premix liquid, and the auxiliary agent is 0.1wt%-2wt% of the weight; S302, printing a 3D bone grafting support pre-treatment body by digital light processing technology, and obtaining the 3D bone grafting support through cleaning, debinding and sintering procedures after the 3D bone grafting support pre-treatment body is printed.

6. The method for preparing a natural tooth composite bone graft scaffold for alveolar bone repair according to claim 5, characterized in that, In step S301, the acrylate monomer includes one or more mixtures of trimethylolpropane triacrylate TMPTA, tripropylene glycol diacrylate TPGDA, 1,6-hexanediol diacrylate HDDA, 4-acryloylmorpholine ACMO, 2-hydroxyethyl methacrylate HEMA; The photoinitiator is one or more mixtures of diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide, phenyl bis (2,4,6-trimethylbenzoyl) phosphine oxide, 2,4,6-trimethylbenzoyl phenyl phosphonic acid ethyl ester, fluoro borate acrylate, 2-hydroxy-2-methyl-1-phenyl-1-propanone; The dispersant includes at least one of sodium tripolyphosphate, carboxymethyl cellulose, sodium polyacrylate, and ammonium polymethacrylate; The auxiliary agent is one or more mixtures of a leveling agent, a defoaming agent, an absorbent, a polymerization inhibitor, an inhibitor, a stabilizer, and a sintering aid.

7. The method of claim 5, wherein the natural tooth composite bone grafting scaffold for alveolar bone repair is prepared by the steps of: (a) mixing the natural tooth composite bone grafting scaffold for alveolar bone repair of claim 5 with a solvent; (b) stirring the mixture; (c) drying the mixture; and (d) pulverizing the dried mixture. In step S301, the preparation of the mixed powder-based photocuring molding slurry includes the following steps: Step 1: obtaining a mixed powder of a natural tooth, a bioactive glass, and a carbon-based material; Step 2: adding 0.5wt%-2wt% of a photoinitiator and an auxiliary agent to the acrylate monomer, stirring for 2h-5h at room temperature by a magnetic stirrer to obtain a resin premix; Step 3: adding 55wt%-75wt% of the mixed powder and 2wt% of the dispersant based on the weight of the mixed powder to the obtained resin premix, and ball milling for 2h-3h or homogenizing for 2min-6min using a homogenizer; wherein the mixed powder is added in three times, and after the addition of the mixed powder, the ball milling is continued for 2h-3h or the homogenizing is continued for 2min-6min using a homogenizer to obtain the mixed powder-based photocuring molding slurry.

8. The method for preparing a natural tooth composite bone graft scaffold for alveolar bone repair according to claim 1, characterized in that, In step S5, the preparation method of the natural tooth composite bone grafting scaffold includes: S401: in an ultra-clean bench, dopamine hydrochloride is dissolved in a Tris-HCL buffer solution with a pH of 8.5; under ventilation and dark conditions, a 3D bone grafting scaffold is placed in the Tris-HCL buffer solution for 12h-48h, and dopamine is self-polymerized and adhered to the scaffold; wherein the Tris-HCL buffer solution is prepared into a solution with a concentration of 1mg / mL-3mg / mL; the 3D bone grafting scaffold is placed in the solution for 12h-48h, and dopamine is self-polymerized and adhered to the scaffold; after modification, the scaffold is washed with sterile deionized water for 3 times to completely remove unbound dopamine; S402: using deionized water, a carbon-based material powder is prepared into a solution, and the above scaffold is placed in the carbon-based material solution for 5min-10min and then taken out, completing the modification to obtain a polydopamine-carbon-based material composite coating modified natural tooth composite bone grafting scaffold; wherein the carbon-based material is prepared into a solution with a concentration of 1mg / mL-3mg / mL.

9. A natural tooth composite bone grafting stent for alveolar bone repair, characterized by, The bone grafting scaffold is prepared by the preparation method of the natural tooth composite bone grafting scaffold for alveolar bone repair according to any one of claims 1-8.

10. A method for designing a natural tooth composite bone grafting scaffold for alveolar bone repair, characterized by, The design method is used for improving the preparation method of the natural tooth composite bone graft support for alveolar bone repair according to any one of claims 1-8, and the design method comprises: (1) Block bone graft support: using computer-aided design to construct a bone graft support model; wherein the internal porous structure of the block bone graft support is a bionic trabecula, a three-period minimal surface, a tetrahedron, a hexahedron, an octahedron, and a diamond structure, the pore size of the support is 250-800 μm, the wire diameter is 100-400 μm, and the porosity is 60-80%; the external structure is a regular shape such as a cylinder, a cube, a rectangle, a ring, and a wedge; (2) Granular bone graft support: using computer-aided design to construct a bone graft support model; wherein the internal porous structure of the granular bone graft support is a bionic trabecula, a three-period minimal surface, a tetrahedron, a hexahedron, an octahedron, and a diamond structure, the pore size of the support is 250-800 μm, the wire diameter is 100-400 μm, and the porosity is 60-80%; the external structure is granular, and the size is 0.5-3 mm; (3) Patient matching type bone graft support: reconstructing alveolar bone according to CBCT image data, virtually repairing alveolar bone defects; determining the three-dimensional shape and size of the customized design support and performing porous design according to the bone defect area; wherein the porous structure of the support is a bionic trabecula structure and a three-period minimal surface structure, the pore size of the support is 250-800 μm, the wire diameter is 100-400 μm, and the porosity is 60-80%.

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